CVE-2026-31951
Medium
Description
LibreChat is a ChatGPT clone with additional features. In versions 0.8.2-rc1 through 0.8.3-rc1, user-created MCP (Model Context Protocol) servers can include arbitrary HTTP headers that undergo credential placeholder substitution. An attacker can create a malicious MCP server with headers containing `{{LIBRECHAT_OPENID_ACCESS_TOKEN}}` (and others), causing victims who call tools on that server to have their OAuth tokens exfiltrated. Version 0.8.3-rc2 fixes the issue.
SeverityMedium
CVSS6.8
Exploit probability—
ProductLibrechat
PublishedMar 27, 2026
First seenMar 27, 2026
Weakness typeCWE-200Sensitive information exposure
How to fix
Update
- librechat librechat0.8.3 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| librechat librechat | 0.8.2 ≤ v < 0.8.3, 0.8.3 | 0.8.3 |
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